With the demands of speeding up and high-quality images of copy machines and laser printers of the recent years, toners are required to have smearing resistance, durability, triboelectric stability, and the like. In addition, with the expansion of the markets, a toner capable of forming high-quality, high-efficiency images against diversified media, further against sheets with diversified grades in a case of paper.
Patent Publication 1 (Japanese Patent Laid-Open No. 2010-152234) discloses a method for forming fused images including the step of after-treating a recording medium to which a toner is fused by heat-and-pressure fusing with a post-treatment machine, thereby forming fused images at a printing speed of 45 m/min or more, wherein the toner comprising toner matrix particles and an external additive, the toner matrix particles containing a resin binder, a colorant, and a specified amount of fluororesin powders having an average particle size of from 0.1 to 1 μm, is used, whereby smearing resistance is excellent and a high-quality image can be maintained even when printing is continued for a long period of time.
Patent Publication 2 (Japanese Patent Laid-Open No. 2010-152225) discloses as a toner having excellent triboelectric stability, transferability, low-temperature fusing ability, and smearing property, a toner containing a resin binder comprising a linear polyester, the linear polyester containing a polyester having a softening point of from 90° to 115° C., obtainable by polycondensing at least a carboxylic acid component comprising an aromatic carboxylic acid compound, and an alcohol component, wherein the toner has a specified particle size distribution, and contains fine fluororesin particles having an average particle size of 1 μm or less in a specified amount.
In addition, Patent Publication 3 (Japanese Patent Laid-Open No. 2008-139851 (corresponding to U.S. Patent Application Publication No. 2008/0107987)) describes a toner comprising toner matrix particles containing at least a resin binder and a colorant, and an external additive coating thereto, wherein the toner in which the above-mentioned toner matrix particles contain fine fluororesin particles having an average particle size of 1 μm or less in a specified amount maintains excellent fused images even in long-term durability printing at a low coverage ratio, so that the toner has excellent fusing ability.
Further, Patent Publication 4 (Japanese Patent Laid-Open No. 2004-286820) discloses a toner for electrostatic image development obtained by dissolving or dispersing at least a prepolymer made of a modified polyester-based resin, a compound capable of extending or crosslinking with the prepolymer, and a colorant in an organic solvent to allow a crosslinking reaction and/or an extension reaction in an aqueous medium, and removing the solvent from the dispersion obtained, characterized in that the toner contains fine fluororesin particles, in which the toner for electrostatic image development meets the needs of a low-temperature fusing system, while maintaining cleanability, has excellent offset resistance, and has a sharp triboelectric charge distribution without soiling fusing apparatuses and fused images, whereby excellently vivid and sharp, visible fused images can be formed over a long period of time.
Moreover, Patent Publication 5 (Japanese Patent Laid-Open No. 2008-139611) discloses, as a method of obtaining a toner having stable properties in triboelectric properties and fluidity even by a long-term use without generating filming to a photoconductor, a method for producing a toner characterized in that the method includes the steps of kneading an internal additive including a releasing agent and a resin binder, pulverizing a kneaded mixture, adding at least a part of an external additive to a pulverized powder, classifying the mixture powder, and recycling a fine powder component outside a given particle size obtained by the above classifying step back to the kneading step, wherein the internally added amount of the above-mentioned external additive contained in the internal part of the above-mentioned toner particles is within a specified range based on the amount of the toner components, excluding the amount of the external additives.